Just Skirts and Dresses: Button tab for sleeves

If ou wonder wether my Alma blouse is sitting on a pile of UFO's, it is not. It just slow progress. The blouse is assembled, the sleeves are set in. 'All' that remains is inserting the invisible zipper and finishing the hem and sleeves. today I thought to 'quickly' whip up the button tabs. Well, what was I thinking... The button tabs for rolled up sleeves aren't part of the original design, so there was no explanation of how to do it (right). First I thought to tackle this the easy way, made sort of tube, turning it inside out and finish it up.

left: this was the idea, right: everything sewn, ready to turn:

I was wrong. Everything went well to the point when you need to turn a small tube inside out...which is normally open at the two ends. Well, mine was closed at three sides, except one of the smaller ends. First I tried to do it with a knitting needle. I almost went through the fabric. Then I tried to do it with a safety pin. Which was really, really hard, and at the end of the process I had to surgically remove it from the fabric. The result: two uneven, ugly wobbly 'tabs' without even a left over of the V-shaped ends:

The method didn't work, so I had to figure out how to to get the job done. I came up with this:
1. Cut fabric to desired length, add about 2x0.5 cm seam allowance.
Fold fabric right sides together, press and pin.

2. Mark the outlines of the tab and pin the edges to prevent sliding of the layers when sewing (you can add a layer of interfacing at this step)

3. Sew along the marked line, leaving one of the longer sides open. I went twice over the V-shape to make the seam stronger. I choose to sew the longer side too to make it symmetric (otherwise there would be one folded side and the other sewed)

4. Trim the corners. After making the picture I actually flattened the corners of the V-shapev end even more.
Also, at this step I thought it would be better to reinforce the fabric with fusible interfacing, so I cut two strips and ironed it to one side. Though it doesn't make a difference the right moment to do this would be step two, before sewing.

5. Turn inside out and press (there is my layer of fusible interfacing)

6. Fold the open edges inside, press and pin:

7. I used the top stitch guide foot of my sewing machine to make the stitching line even at the long sides, but you can use a regular foot too. (I sewed the V-part with a regular foot because I didn't find it easy to make sharp corners with the needle out of the center)